At certain low speeds the car felt like it was jerking, as if it were constantly downshifting. At other times I felt a rumbling, as though I were driving over a rough rode. It turned out to be a bad torque converter, and I had to have the transmission rebuilt. I also replaced the radiator (Valeo) which are known to fail and leak coolant into the transmission, causing the torque converter to fail. Valeo radiators were used in early 2004 mod...